Monitoring electrode voltages in an implantable medical device system having daisy-chained electrode-driver integrated circuits

Abstract

Electrode voltage monitoring circuitry for an implantable neurostimulator system having a plurality of electrode-driver integrated circuits (ICs) in provided. Electrodes from either or both ICs can be chosen to provide stimulation, and one of the IC acts as the master while the other acts as the slave. Electrodes voltages on the slave IC are routed to the master IC, and thus the master IC can monitor both electrode voltages on the slave as well as electrode voltages on the master. Such voltages can be monitored for a variety of purposes, and in particular use of such voltage is disclosed for determining the resistance between electrodes and to set a compliance voltage for stimulation.

What is claimed is: 
     
       1. An implantable stimulator device, comprising:
 a first integrated circuit, comprising:
 a plurality of first electrodes configured to provide stimulation to a patient's tissue, 
 a first selector circuit, the first selector circuit receiving at least the first electrodes as first inputs and configured to select a first voltage from the first inputs, and 
 a second selector circuit, the second selector circuit receiving at least the first electrodes as second inputs and configured to select a second voltage from the second inputs; and 
 
 a second integrated circuit, comprising:
 a plurality of second electrodes configured to provide stimulation to a patient's tissue, 
 a third selector circuit, the third selector circuit receiving at least the second electrodes and the first and second voltages as third inputs and configured to select a third voltage from the third inputs, and 
 a fourth selector circuit, the fourth selector circuit receiving at least the second electrodes and the first and second voltages as fourth inputs and configured to select a fourth voltage from the fourth inputs. 
 
 
     
     
       2. The device of  claim 1 , wherein the third and fourth selector circuits further receive at least one DC voltage. 
     
     
       3. The device of  claim 2 , wherein the DC voltage is selected from the group consisting of ground, a voltage of a battery in the device, and a compliance voltage for powering stimulation circuitry in the device. 
     
     
       4. The device of  claim 1 , wherein the second integrated circuit further comprises holding circuitry for receiving the third and fourth voltages. 
     
     
       5. The device of  claim 4 , wherein the third and fourth voltages are received across the holding circuitry. 
     
     
       6. The device of  claim 5 , wherein the second integrated circuit further comprises a differential amplifier for receiving the third and fourth voltages. 
     
     
       7. The device of  claim 1 , wherein the first and second integrated circuits are of identical construction. 
     
     
       8. The device of  claim 1 , further comprising a conductive case for housing the first integrated circuit and the second integrated circuit, and wherein at least one of the first, second, third or fourth selector circuits additionally receives a voltage of the case as an input. 
     
     
       9. An implantable stimulator device, comprising:
 a first integrated circuit comprising a plurality of first electrodes configured to provide stimulation to a patient's tissue; and 
 a second integrated circuit comprising a plurality of second electrodes configured to provide stimulation to the patient's tissue, and measurement circuitry configured to select two voltages, wherein the two voltages are selected from the group consisting of a voltage of one of the first electrodes, a voltage of one of the second electrodes, ground, a voltage of a battery in the device, a compliance voltage for powering stimulation circuitry in the device, and a voltage of the case for the device, 
 wherein the two voltages are impressed across a capacitor in the measurement circuitry. 
 
     
     
       10. The device of  claim 5 , further comprises an amplifier for outputting a difference between the two voltages. 
     
     
       11. The device of  claim 9 , wherein the first and second integrated circuits are of identical construction. 
     
     
       12. An implantable stimulator device, comprising:
 a first integrated circuit comprising a plurality of first electrodes configured to provide stimulation to a patient's tissue; and 
 a second integrated circuit comprising a plurality of second electrodes configured to provide stimulation to the patient's tissue, and measurement circuitry configured to select a first voltage from the first and second electrodes, and a second voltage comprising a DC voltage, 
 wherein the DC voltage is selected from the group consisting of ground, a voltage of a battery in the device, a compliance voltage for powering stimulation circuitry in the device, and a voltage of the case for the device, 
 wherein the second integrated circuit further comprises an amplifier for outputting a difference between the first and second voltages. 
 
     
     
       13. The device of  claim 12 , wherein the measurement circuitry comprises a capacitor. 
     
     
       14. The device of  claim 13 , wherein the first and second voltages are impressed across the capacitor. 
     
     
       15. The device of  claim 13 , wherein the first and second integrated circuits are of identical construction.